Study On Traffic Characteristics And Safety Control Of Xinjiang Expressway Under Rain And Snow Conditions

With the change of global climate, the adverse weather has been involved into all aspects of people’s lives, especially the road traffic safety performance. Climate characteristics of Xinjiang are quite unique in the nation, in which the adverse weather occupies a large proportion, and causes extremely serious impact on the traffic operation. Also, the probability of car skidding, tail flick, scraping and overturning traffic accident are extremely high due to snowfall and rainfall, and even lead the local traffic to a standstill. To alleviate this problem, traffic flow characteristic analysis under the adverse weather becomes very important. Therefore it is in great need to conduct systematic, comprehensive, scientific analysis and research on flow characteristics under different grades of inclement weather conditions and master the rules that provide a scientific and effective theoretical basis in order to formulate reasonable traffic safety management measures.Firstly the scheme of data collection is based on video and artificial auxiliary, and the Autoscope and artificial processing are utilized to obtain the traffic flow parameters, after which the traffic states in rain and snow are selected as the object of study. The meteorological snow statistics of recent years in north of Xinjiang high speed along the main city are collected and used to study the variation characteristics of Xinjiang snow temporal and spatial variation characteristics and snowfall days, thus the most serious three areas and abnormal affected section have been focused. Secondly, according to the influence of the snow and rain weather on road safety, the multi-model comparison test method are conducted to study the characteristics of speed, vehicle arrival rate under different snow level, then the method of nonlinear regression analysis is utilized to find the rules of different rainfall intensities on different lanes of traffic flow. The results presents the decrease of snowfall rate, vehicle arrival rate and the increase of headway. With the increase of velocity, flow reduction degree, rainfall of the same intensity affects more significantly on high-speed Lane than slow lane, but the rules are basically the same.Then we use Matlab to establish the scatter plot of speed, flow and density, and choose the curve fitting and the linear regression model to obtain the expression of the three parameters. The results show that: compared with the normal weather, under the joint action of velocity and flow rate, traffic state trends to congestion with the increase of snowfall; and under the joint action of velocity and density, with increasing snowfall, vehicle density variation amplitude increases in correspond with different vehicle speed under the same weather.Finally on the basis of the former research, speed model and safe braking model are utilized to propose the recommend value on the snow and rainfall of speed limits and safety distance, controlling the adverse weather influence on highway safety.